For two reasons.
Bethesda has announced that Fallout 4 will be released for the Xbox One, PlayStation 4, and Windows PC on November 10, 2015.
This news is surprising considering Bethesda released their last two action RPG "Fallout" games 15-18 months after they released a teaser trailer for those games. They also released both of those games in October.
Because of those reasons, a lot of fans predicted an October 2016 release for Fallout 4. Bethesda surprised us, huh?
You can pre-order Fallout 4 on Amazon.com
Speaking of "Fallout" and "Amazon.com," that store currently has the downloadable Windows PC version of Fallout: New Vegas